Therapeutic ultrasound devices have long been utilized in the treatment of musculoskeletal and tissue injuries. Greater understanding of ultrasound, and the application of ultrasound to human skin and tissue, have expanded the scope of possible uses for these devices. For instance, in addition to the thermal or vibratory focus of more traditional devices, developments have been made in which ultrasound devices can be directed toward introducing various drugs into the human body through the skin. However, the increase in potential uses and advantages for these therapeutic ultrasound devices has come at a price. Namely, advancements in the technology and the understanding of the potential applications, has correspondingly led to the complication of setup procedures, inefficient power adjustments, and the need for more precise calibration procedures.
Initial Parameter Inputs
Ultrasonic therapy devices impose mechanical vibrations on tissue and skin to cause various thermal and non-thermal effects. An ultrasound generator outputs electric power to a treatment head. The treatment head includes a transducer which converts the power from the generator into ultrasonic energy or acoustic power. It is this acoustic power that is transmitted for therapeutic treatment through the patient's tissue. The requisite acoustic power can vary greatly depending on the treatment goals, the target tissue type, the target tissue depth, and other like factors. In addition, the duration of the ultrasonic treatment dosage to the patient is important. Treatment goals, the unique characteristics of the target tissue, and like considerations dictate the treatment duration.
Conventional ultrasound treatment devices generate a treatment dose based on manually inputted values or parameters. Parameters such as treatment time/duration, frequency, and treatment intensity are inputted by the end user. Generally, with such devices, calculations and determinations are made by the user. Consequently, it is up to the device user to come up with the ideal treatment parameters required for a specific patient, assuming specific treatment goals for that patient.
There are many drawbacks with manually operated devices. Specifically, it is problematic that these manual systems are reliant upon the skills and knowledge of the individual user. This problem manifests itself in at least two respects. First, there is no way to know or control exactly what factors are being considered by the user in calculating the proper treatment parameters. For example, there are no guarantees that the end user will properly consider the target tissue characteristics, the target tissue type, or the existence and depth of any intermediate tissue between the treatment head and the target tissue. These are all highly relevant factors that should play a primary role in determining the proper treatment outputs and durations for any effective ultrasound therapeutic treatment. In addition, accidental parameter entries, and the varying level of user training introduce still more uncertainty into the likelihood of providing optimized ultrasound treatment for the patient.
As indicated, the unique and specific characteristics of the target tissue, and the nature and thickness of intermediate tissue and/or the target tissue, are requisite factors to be considered in determining a proper ultrasound treatment dose. This is true since both the thermal and non-thermal effects of ultrasound are dependent upon these factors. Despite the fundamental importance of these considerations, conventional ultrasound therapeutic devices simply have not advanced methods and apparatus that properly consider and process known histological tissue characteristics in generating a treatment dose.
U.S. Pat. No. 5,413,550 (“the '550 Patent”) discloses an attempt to provide for considerate dose control. The '550 Patent is directed to an ultrasound device including a controller programmed to calculate a treatment dose. The treatment dose consists of treatment frequency, output intensity, and treatment time. The programmed controller determines and generates the dosage parameters based on the inputting of numerous treatment parameters by the end user. Specifically, the device requires values for the following primary treatment parameters in order to calculate a dosage: depth of tissue to be treated, the desired tissue temperature rise, the tissue area to be treated, and the selection of an ultrasound couplant. In addition the user may input the tissue type, and a duty factor value as secondary parameters.
The device of the '550 patent performs routine checks to determine if treatment parameters have been entered. If the controller determines that specific primary treatment parameters have not been inputted, the controller circuitry inserts a default value in place of the missing parameter(s). As a result, it is possible to enter only one of the primary treatment parameters, with each of the remaining parameters being substituted for default values. Such a default-driven device and process is problematic and fails to properly focus the ultrasound treatment on ultrasound effects and histological tissue data.
The use of default parameters to calculate dosage, by definition, fails to take into account the unique circumstances and characteristics of the patient, the treatment goals for the specific target tissue of the patient, and like goals and considerations that are essential in providing highly efficient and effective ultrasound treatment. As indicated herein, knowledge and specific consideration of the unique target treatment tissue, and the depth of that tissue or the thickness of intermediate tissue, are essential in generating an optimal treatment dose. Generating a dose, regardless of the automated nature of the calculation, is deficient if it fails to account for the true tissue structure, such as the energy losses produced as a result of tissue heating, and the losses caused by adjacent tissue structure. Ignoring such essential characteristics of treatment on complex tissue structures dilutes the efficacy of the dosage calculation. Proper acoustic power outputs and treatment durations must be specified, monitored, and updated in a manner most beneficial for the treatment goals for the unique individual patient, after fully understanding and processing data pertaining to the target tissue, intermediate tissue, and tissue depths.
Treatment Dose Adjustments
Conventional ultrasonic therapeutic devices and systems are generally deficient when it comes to the continuous and efficient monitoring and controlling of the power being outputted from the generator to the transducer. The typical approach to controlling, acoustic power from the transducer head is to merely provide alarm and display notices to the user. For example, U.S. Pat. No. 4,791,915 is directed to a device wherein the coupling efficiency between the transducer and the patient is displayed in the form of a readable bar graph for the user to observe and monitor. However, such systems and devices merely focus on preventing overheating and electrical shorting. Threshold comparisons are merely made in order to prevent catastrophic failures which could cause device malfunction and/or injury to the patient.
Other conventional ultrasound treatment systems implement adjustment techniques and controls directed to providing for a relatively constant electric power output level to the patient. For instance, U.S. Pat. No. 4,368,410 discloses an ultrasound therapy device wherein an optimal electric output power level is inputted into the device. Feedback signals from a driver circuit proportional to the transducer voltage and current are returned to an analog servo circuit and a voltage representing true electric power is calculated. If the output power represented by the voltage level increases then it is an indication that there is a reduction in the load on the transducer, and the drive signal is decreased. Similarly, if the instant voltage decreases, an increase in the signal is initiated to compensate for an increase in the load on the transducer. The innate problem with such a system is that while it does acknowledge the effects varying treatment techniques, treatment zones, and an individuals body can have on ultrasound treatment, it does not properly use this information in providing for a truly responsive individualized treatment dosage. Focus is on maintaining a constant electric power output and not on performing acoustic analysis. Events and circumstances effecting the ultrasound treatment are not properly considered—i.e., the introduction of intermediate tissue, the natural changes across a patient's body “zones”, and the like.
Treatment Head Calibration
Each treatment head of an ultrasound therapeutic device requires calibration. Primarily, this calibration is needed in order to accommodate and adjust for, various innate properties and characteristics unique to particular heads. The head must be properly calibrated in order to correctly match the specific resonance frequencies of its constituent ceramic. For instance, each ceramic treatment head varies in its material properties. As a result, proper operation and acoustic output for each and every head mandates at least an initial head calibration. Typically, this calibration is done in the factory prior to receipt of the device by the end user. In many cases, this is the only calibration allowed for, and any later re-calibration must again occur at the factory. However, these factory calibrations are problematic since untimely degeneration can adversely affect treatment quality and effectiveness.
Even those conventional devices that permit for user-initiated calibration require the initiation of complicated or time-consuming procedures. Specifically, it is common to allow for user calibration by immersing the head in water and making a series of adjustments based on calibration readings displayed by the device. For obvious reasons, such techniques are undesirable and inconvenient. Additionally, conventional devices do not consider complex changes introduced by slight imaginary components in the acoustic impedance of the tissues being treated. Conventional devices are thus unable to transmit an accurate amount of power to the tissue or fully self-calibrate.
As a result, there is a need for an ultrasonic therapeutic device, and method for operating and controlling thereof, that substantially solves the problems and deficiencies described in the prior art.